The external shape of such a tire bead is described among other characteristics in U.S. Pat. No. 6,092,575. The external shape and in particular the axially outer wall of the bead is axially set back relative to the axially outermost end of the rim; consequently, the axially outermost metallic parts of the rim are not protected against aggressions due to curbs, for example, during urban driving. The particular structure of the bead, whose heel is axially on the inside and whose toe is axially on the outside, is described in U.S. Pat. No. 6,179,028: the turning-up of the carcass reinforcement around the anchoring bead wire and a wedge of rubber mixture with high hardness and essentially triangular shape, results in the presence of reinforcing elements of the carcass reinforcement close to the axially outer wall of the bead, and consequently to the possibility that such elements may be damaged. The desire to ensure simultaneous protection of the metallic parts of the rim and of the reinforcing elements of the carcass reinforcement led the applicant to adapt the axially outer shape of the toe of the bead, an adaptation that resulted in covering the edge of the outer hump of the rim with a more or less large mass or protuberance of rubber of appropriate quality, which made the maximum axial width of the external contour of the toe of the bead greater than the bulk or maximum axial width of the mounting rim.
Although this protuberance provides satisfactory protection for the corresponding hump of the rim, it is in contrast very sensitive on the one hand to abrasion when the tire scrapes against an external object such as a kerbside and on the other hand to the detachment of bits of rubber resulting from the initiation and propagation of cuts and/or breaks. International application PCT 99/64258 recommends providing said protuberance with incisions of non-zero width and depth at most equal to 5 mm, these incisions delimiting ribs orientated essentially in the meridian direction and parallel to one another.
The solution described above is not totally satisfactory from the standpoint of rubber detachment, with the consequence of damage to the carcass reinforcement upturn that is hardly compatible on the one hand with aesthetic appearance and on the other hand with the need for safety, both naturally being demanded by the users.
The purpose of the present invention is to propose a different solution to overcome the drawbacks described above, and consists in replacing the protuberance of the bead designed to be radially in contact with the rim hump by a protective rib or protuberance of appropriate shape, positioned in a suitable way.